1. Field of the Invention
The present invention relates to a ceramic-metal composite body in which a ceramic member is fitted to a metallic member by a mechanical means.
2. Related Art Statement
Since ceramics such as zirconia, silicon nitride, and silicon carbide are excellent in mechanical strength, heat resistance, and wear resistance, they are noted as high temperature structural materials such as gas turbine engine parts, reciprocating engine parts, wear resistant materials, etc. However, ceramics are generally hard and brittle, and therefore, have a poor forming workability as compared with metallic materials. Further, since ceramics are poor in toughness, they have weak impact resistance. For this reason, it is difficult to form machine parts, such as engine parts, from a ceramic material only. Thus, ceramics are ordinarily used in a composite structure in which a metallic member and a ceramic member are fitted together.
As methods of fitting a ceramic member and a metallic member, there are known methods of forming composite bodies by means of fitting a projection of the ceramic member into a depression of the metallic member, that is, by means of a press fitting, expansion fitting, contraction fitting and so on.
There have been various reports on the optimum ranges of temperatures, profiles, etc. at the time of these fittings. For instance, Japanese Patent Application Laid-open No. 60-50,204 describes that a ceramic-metal composite body with excellent properties can be obtained through fitting when the diameter of a projection formed on a ceramic member is made larger by 0.5% to 5% than the inner diameter of a depression formed in a metallic member.
However, these prior art techniques are all directed to limitations on the profile, temperature, etc. prior to the fitting. Therefore, they have shortcomings that a fitting force is unsatisfactory, or a stress is excessive, for instance, depending upon the shape and size of an intended article, use conditions such as temperature, etc., so that ceramic-metal composite bodies with excellent properties can not be obtained. That is, the above-mentioned prior art techniques can not always provide composite bodies with excellent properties for the ceramic-metal composite bodies.